The capital markets are essential components of the world's economies. Through these markets, among other things, companies and governments can raise money to support their operations by selling securities (such as stocks and bonds) to investors.
A wide variety of mechanisms are available for buying and selling securities. These include stock exchanges (e.g., the New York Stock Exchange), electronic liquidity providers (ELPs), dark pools, and alternative trading systems. A dark pool is an aggregation of undisclosed liquidity that attempts to hide the available liquidity for a given security so that the price for the security is not adversely impacted by the liquidity.
It is desirable in many instances to be able to execute trades through a combination of these different mechanisms, and control the manner in which those trades are routed and posted.